The present invention relates to a ferroelectric capacitor, a method of manufacturing the ferroelectric capacitor, a ferroelectric memory, and a piezoelectric device.
A ferroelectric memory (FeRAM) retains data by spontaneous polarization of a ferroelectric capacitor using a ferroelectric film. In the ferroelectric memory, the crystallization state of the ferroelectric film included in the ferroelectric capacitor is one of the factors which determine the characteristics of the device. The manufacturing steps of the ferroelectric memory include a step of forming an interlayer dielectric and a protective film, in which a process which generates a large amount of hydrogen is used. Since the ferroelectric film is substantially formed of an oxide, the oxide may be reduced by hydrogen generated during the manufacturing steps and adversely affect the characteristics of the ferroelectric capacitor.
Therefore, in a conventional ferroelectric memory, the ferroelectric capacitor is covered with a barrier film such as an aluminum oxide film or an aluminum nitride film in order to prevent deterioration of the characteristics of the ferroelectric capacitor, thereby securing reduction resistance of the capacitor. However, such a barrier film occupies a surplus region when increasing the degree of integration of the ferroelectric memory. Moreover, a technology capable of manufacturing a ferroelectric memory using a simplified process is demanded from the viewpoint of productivity.